Method and system for multirobot collaborative mobile manipulation

Abstract

A robot system includes a plurality of mobile manipulator robots, where each mobile manipulator robot includes a mobile robot base, a robot manipulator mounted to the mobile robot base, and one or more computers in communication with the mobile robot base and the robot manipulator. The robot manipulator includes an end-effector that incorporates passive compliance due to spring elements at one or more joints of the robot manipulator. The one or more computers coordinate motion control of the mobile robot base and force control at the end-effector of the robot manipulator to manipulate a payload in cooperation with other mobile manipulator robots of the plurality, while collaborating with zero, one, or a plurality of human users that are in contact with the payload.

What is claimed is: 
     
         1 . A robot system comprising:
 a plurality of mobile manipulator robots, wherein each mobile manipulator robot includes:   a mobile robot base;   a robot manipulator mounted to the mobile robot base, wherein the robot manipulator includes a Delta robot, and wherein each actuated joint of each Delta robot is driven by a series-elastic actuator; and   one or more computers in communication with the mobile robot base and the robot manipulator, wherein the one or more computers are configured to simultaneously:   coordinate motion control of the mobile robot base and force control of the robot manipulator to manipulate a payload in cooperation with other mobile manipulator robots of the plurality; and   collaborate with zero, one, or a plurality of human users that are in contact with the payload.   
     
     
         2 . The robot system of  claim 1 , wherein each series-elastic actuator includes a pair of antagonistic springs connecting an actuator-driven yoke to a link of the Delta manipulator. 
     
     
         3 . The robot system of  claim 1 , wherein an encoder-instrumented unactuated gimbal with three degrees of freedom is mounted to the Delta robot. 
     
     
         4 . The robot system of  claim 1 , wherein each mobile robot base comprises a wheeled robot base. 
     
     
         5 . The robot system of  claim 4 , wherein the wheeled robot base comprises an omnidirectional wheeled robot base. 
     
     
         6 . The robot system of  claim 1 , wherein the mobile manipulator robots communicate wirelessly with each other or a central control station. 
     
     
         7 . The robot system of  claim 1 , wherein each mobile robot base is configured to sense its position and orientation. 
     
     
         8 . A robot manipulator comprising:
 a Delta robot, wherein each actuated joint of the Delta robot is driven by an actuator incorporating one or more spring elements;   one or more computers in communication with the Delta robot and configured to measure and control translational forces in a frame fixed to a moving output platform of the Delta robot; and   an encoder-instrumented unactuated gimbal with three degrees of freedom mounted to the moving output platform of the Delta robot.   
     
     
         9 . The robot manipulator of  claim 8 , further comprising a mobile robot base to which the Delta robot is mounted. 
     
     
         10 . The robot manipulator of  claim 9 , wherein the mobile robot base is an omnidirectional wheeled mobile robot. 
     
     
         11 . A method of controlling a plurality of mobile manipulator robots, the method comprising simultaneously achieving, by a computing system, a desired linear force in a frame fixed to an output platform of a Delta robot while driving a mobile base to keep the output platform of the Delta robot as close as possible to a center of a workspace in which the Delta robot is operating. 
     
     
         12 . The method of  claim 11 , further comprising determining, by the computing system, forces to be applied to a payload by the plurality of mobile manipulator robots collectively to cause the payload to feel weightless to one or more human users contacting the payload. 
     
     
         13 . The method of  claim 11 , further comprising collectively estimating, by the mobile manipulator robots, a mass and one or more inertial properties of a payload that is to be manipulated. 
     
     
         14 . The method of  claim 11 , wherein the computing system comprises a central control station. 
     
     
         15 . The method of  claim 11 , further comprising determining, by one or more sensors and the computing system, a position and an orientation of the mobile base. 
     
     
         16 . The method of  claim 15 , wherein the encoder-instrumented unactuated gimbal has three degrees of freedom. 
     
     
         17 . The method of  claim 11 , wherein each actuated joint of each Delta robot is driven by a series-elastic actuator.